1. Field of the Invention
The present invention relates to a method for deodorizing and refreshing solvent (i.e., removing odor from solvent) of the petroleum group used as cleaning liquid in a dry cleaning apparatus, and a dry cleaning apparatus using such a method.
2. Prior Arts
There are four kinds of solvents used in dry cleaning in the present time, i.e., petroleum group solvent, freon, trichloroethane and perchloroethylene. Nowadays, the petroleum group solvent is used the most while the use of freon and trichlorocthane is scheduled to be prohibited in the near future from the viewpoint of environmental pollution. Accordingly, the Increasing use of the dry cleaning apparatus using the petroleum group solvent is expected.
Problems to be Solved by the Invention
Since the emission regulation regarding the petroleum group solvent is not so strict in comparison to regulation governing the use of other solvents, the dry cleaning apparatus using the petroleum group solvent has less sealing ability than the dry cleaning apparatuses which use other solvents. Thus, the surroundings are contaminated by an offensive odor emitted from the volatilized petroleum group solvent and a bad smell emitted from accumulated polluted matter dissolved out of clothes or the like (i.e., laundry) which are being cleaned, and such offensive odors adhere to the cleaned clothes or the like.
In the dry cleaning apparatuses using the petroleum group solvent, since the solvent is stored in a solvent storage tank and is circulated to be re-used, the solvent is gradually polluted and worsened by the polluted matter dissolved out of the laundry as the cleaning is repeated. Normally, the dry cleaning apparatus using the petroleum group solvent has a filter for removing the polluted matters suspended in the solvent. However, such a filter cannot remove fine suspended matter and soluble dirt.
Further, filters incorporating absorbent such as active carbon therein have been proposed, and the filter has been used together with the absorbent. In such cases, the fine suspended matter and soluble dirt can be removed to some extent, but cannot be removed completely. Thus, the polluted components gradually accumulate in the solvent. Further, if the efficiency of the absorbent is worsened, the pollution of the solvent will be increased rapidly. The service life of the absorbent depends upon the degree of pollution in the laundry and/or cleaning conditions.
For example, in case of following cleaning method, the efficiency of absorbent is worsened in 3-7 days.
(1) Total cleaning laundry is about 700 kg a day.
(2) Combining batch cleaning for cleaning 20-25 kg each time, and filter circulation cleaning for overflowing the solvent and circulating the solvent through the filter.
(3) Cleaning time is about 8 minutes in each cycle.
Thus, it is difficult for the user to constantly maintain the solvent in a fresh condition, and such maintenance is very expensive. Further, even if the solvent is kept in fresh condition, the degree of recovery of cleaning ability of the solvent and washing ability is insufficient. In addition, if the dirty solvent is used without removing the polluted components, the laundry will be polluted by the solvent, thereby reducing the quality of the laundry.
Further, there is a method of purifying the solvent by utilizing distillation. In this case, however, the distillation has a limitation regarding the amount of the solvent to be purified. Accordingly, in the circulating solvent in a dry cleaning apparatus in which the dirt or pollution is constantly added or increased as the cleaning operation continues, it is very difficult to constantly maintain the solvent in the predetermined fresh condition. Further, notwithstanding the use of the Inflammable petroleum group solvent, since there is no positive measure to counter Ignition and explosion, accidental explosion or fires sometimes occur.